首先，先上最终的效果图

效果并不是很好看，但是这不是重点。

首先，我们先看下布局，

<template>
    <div class="shopcar" id="demo04">
        <div class="header-title">
            <h3>购物车</h3>
        </div>
        <div class="car-list">
            <ul>
                <li class="car-item" v-for="(item,index) in good_list">
                    <div class="input-block">
                        <label class="input-label" :class="{active: item.is_selected}" :for="'car-checkbox-'+index" @click="select_one(index)"></label>
                    </div>
                    <div class="car-item-content">
                        <div class="car-img">
                            <img :src="item.img" />
                        </div>
                        <div class="car-cont">
                            <h3>{{item.title}}</h3>
                            <div class="cat-desc">
                                <span v-for="spec in item.spec_item">{{spec}}</span>
                            </div>
                        </div>
                        <div class="num">
                            <span @click="reduce(index)">-</span>
                            <span>{{item.num}}</span>
                            <span @click="add(index)">+</span>
                        </div>
                        <div class="car-price">
                            <span class="car-price">￥{{item.price}}</span>
                            <span class="car-num">X{{item.num}}</span>
                        </div>
                    </div>
                </li>
            </ul>
        </div>
        <div class="car-footer">
            <div class="foot-car">
                <label for="foot-check" class="input-label" :class="{active: selected_all}" @click="slect_all"></label>
            </div>
            <div class="total-cont">
                <span>总价：{{totalPrice}}</span>
                <span>共{{totalNum}}件</span>
            </div>
            <div class="btn-box">
                <button>立即下单</button>
            </div>
        </div>
    </div>
</template>

非常常见的布局，微商城购物车随处可见，先说明下，在这里，实现选中的功能并不是用传统的label+checkbox实现，而是一个单独的label，目的是为了简化dom结构，在传统的jq项目或者zepto项目中，一般会会这样写，主要是为了方便操作demo，但是vue项目完全不用考虑dom的操作，怎么方便怎么来就ok。

在加些简单的样式，

    .header-title
        height 42px
        line-height 42px
        background #f5f5f5
        border-bottom 1px solid #ddd
    .header-title h3
        font-weight normal
        text-align center
    .car-list 
        background #f2f2f2
        margin-top 12px
        padding 8px
    .car-item
        border-bottom 1px solid #ddd
        position relative
        height 76px
        overflow hidden
    .car-checkbox
        display none
    .input-block
        width 30px
        float left
        height 55px
        line-height 55px
    .input-label
        cursor pointer  
        position absolute  
        width 18px  
        height 18px  
        top 18px  
        left 0  
        background #fff  
        border:2px solid #ccc
        border-radius 50%
    .input-label:after 
        opacity 0  
        content ''  
        position absolute  
        width 9px  
        height 5px  
        background transparent  
        top 6px  
        left 6px  
        border 2px solid #333  
        border-top none  
        border-right none  
        -webkit-transform rotate(-45deg)  
        -moz-transform rotate(-45deg)  
        -o-transform rotate(-45deg)  
        -ms-transform rotate(-45deg)  
        transform rotate(-45deg)  
    .car-img
        width 64px
        height 64px
        float left
        overflow hidden
    .car-img img
        width 100%
    .input-label.active
        background #F15A24
    .car-cont 
        margin-left 100px
    .car-cont h3
        font-weight normal
        line-height 24px
        font-size 14px
    .car-price 
        position absolute
        right 12px
        bottom 0px
        width 40px
        height 40px
        text-align right
    .car-price span
        display block
        height 24px
        line-height 24px
        width 100%
    .car-footer 
        height 60px
        background #f5f5f5
        position fixed
        bottom 0
        left 0
        right 0
    .foot-car
        width 42px
        height 60px
        float left
        margin-left 12px
        position relative
    .total-cont 
        height 60px
        line-height 60px
        font-size 16px
        float left
    .total-cont span
        display inline-block 
        margin-left 12px
    .btn-box
        float right
        height 60px
        line-height 60px
    .btn-box button
        height 100%
        width: 100px
        border none
        background #F15A24
        color #fff
        font-size 16px
    .num
        position absolute
        top 28px
        right 25px
        width 120px
    .num span
        display inline-block
        width 28px
        height 28px
        float left
        text-align center
        line-height 28px
        border 1px solid #ddd
        font-size 14px

最近在学习stylus的使用，所以，就当做练习了。
接下就是javascript了，

export default {
        data () {
            return {
                good_list: [
                    {
                        title: 'Apple iPhone 6s 16GB 玫瑰金色 移动联通电信4G手机',
                        img: "http://sc.tywebs.cn/public/upload/goods/2017/04-27/a767693b9a84747f25335f0e33d3d380.jpg",
                        num: 2,
                        price: 6070.00,
                        spec_item:[
                            '内存:16G',
                            '网络:4G',
                            '颜色:玫瑰金'
                        ],
                        is_selected: false
                    },{
                        title: 'Apple iPhone 6s 32GB 玫瑰金色 移动联通电信4G手机',
                        img: 'http://sc.tywebs.cn/public/upload/goods/2017/04-27/a767693b9a84747f25335f0e33d3d380.jpg',
                        num: 2,
                        price: 4570.00,
                        spec_item:[
                            '内存:32G',
                            '网络:4G',
                            '颜色:玫瑰金'
                        ],
                        is_selected: true
                    },{
                        title: 'Apple iPhone 6s 8GB 玫瑰金色 移动联通电信4G手机',
                        img: 'http://sc.tywebs.cn/public/upload/goods/2017/04-27/a767693b9a84747f25335f0e33d3d380.jpg',
                        num: 2,
                        price: 4870.00,
                        spec_item:[
                            '内存:8G',
                            '网络:4G',
                            '颜色:玫瑰金'
                        ],
                        is_selected: false
                    },{
                        title: 'Apple iPhone 6s 128GB 玫瑰金色 移动联通电信4G手机',
                        img: 'http://sc.tywebs.cn/public/upload/goods/2017/04-27/a767693b9a84747f25335f0e33d3d380.jpg',
                        num: 2,
                        price: 10568.00,
                        spec_item:[
                            '内存:128G',
                            '网络:4G',
                            '颜色:玫瑰金'
                        ],
                        is_selected: true
                    },
                ],
                totalPrice: 0,
                totalNum: 0,
                selected_all: false
            }
        },
        mounted: function () {
            this.getTotal();
        },
        watch: {
            'good_list': {
                handler: function (val, oldVal) {
                    // console.log(val)
                    return val;
                },
                deep: true
            }
        },
        methods: {
            getTotal () {
                this.totalPrice = 0
                this.totalNum = 0
                for (var i = 0; i < this.good_list.length; i++) {
                    var _d = this.good_list[i]
                    if(_d.is_selected){
                        this.totalPrice += _d['price'] * _d['num']
                        this.totalNum +=_d['num']
                    }
                }
            },
            select_one (index) {
                if(this.good_list[index].is_selected == true){
                    this.good_list[index].is_selected = false
                }else{
                    this.good_list[index].is_selected = true
                }
                this.getTotal()
            },
            slect_all () {
                if(this.selected_all){
                    for (var i = 0; i < this.good_list.length; i++) {
                        this.good_list[i].is_selected = false;
                    }
                    this.selected_all = false                       
                }else{
                    for (var i = 0; i < this.good_list.length; i++) {
                        this.good_list[i].is_selected = true;
                    }
                    this.selected_all = true                        
                }
                this.getTotal()
            },
            reduce (index) {
                if(this.good_list[index].num <= 1) return;
                this.good_list[index].num --
                this.getTotal()
            },
            add (index) {
                this.good_list[index].num ++
                this.getTotal()
            }
        }
    }

这里用mock数据来代替后台请求数据的动作，为了方便测试，逻辑比较简单，首先getTotal这个方法用来计算选中的item的数量以及总价，select_one用来处理单个选中的逻辑，slect_all 用来处理全部选中以及全部取消选中的操作，reduce用来处理处理减操作，顾名思义add用来处理加的操作。当然在真实的开发中，还会有校验库存的动作，每次加减都要校验库存。数据处理也会更复杂，但是闻琴弦而知雅意，器原理都是相通的。

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